<?php

/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Gdata
 * @subpackage App
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Util.php 23775 2011-03-01 17:25:24Z ralph $
 */

/**
 * Utility class for static functions needed by Zend_Gdata_App
 *
 * @category   Zend
 * @package    Zend_Gdata
 * @subpackage App
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Gdata_App_Util {
	
	/**
	 * Convert timestamp into RFC 3339 date string.
	 * 2005-04-19T15:30:00
	 *
	 * @param int $timestamp
	 * @throws Zend_Gdata_App_InvalidArgumentException
	 */
	public static function formatTimestamp($timestamp) {
		$rfc3339 = '/^(\d{4})\-?(\d{2})\-?(\d{2})((T|t)(\d{2})\:?(\d{2})' . '\:?(\d{2})(\.\d{1,})?((Z|z)|([\+\-])(\d{2})\:?(\d{2})))?$/';
		
		if (ctype_digit ( $timestamp )) {
			return gmdate ( 'Y-m-d\TH:i:sP', $timestamp );
		} elseif (preg_match ( $rfc3339, $timestamp ) > 0) {
			// timestamp is already properly formatted
			return $timestamp;
		} else {
			$ts = strtotime ( $timestamp );
			if ($ts === false) {
				require_once 'Zend/Gdata/App/InvalidArgumentException.php';
				throw new Zend_Gdata_App_InvalidArgumentException ( "Invalid timestamp: $timestamp." );
			}
			return date ( 'Y-m-d\TH:i:s', $ts );
		}
	}
	
	/** Find the greatest key that is less than or equal to a given upper
	 * bound, and return the value associated with that key.
	 *
	 * @param integer|null $maximumKey The upper bound for keys. If null, the
	 * maxiumum valued key will be found.
	 * @param array $collection An two-dimensional array of key/value pairs
	 * to search through.
	 * @returns mixed The value corresponding to the located key.
	 * @throws Zend_Gdata_App_Exception Thrown if $collection is empty.
	 */
	public static function findGreatestBoundedValue($maximumKey, $collection) {
		$found = false;
		$foundKey = $maximumKey;
		
		// Sanity check: Make sure that the collection isn't empty
		if (sizeof ( $collection ) == 0) {
			require_once 'Zend/Gdata/App/Exception.php';
			throw new Zend_Gdata_App_Exception ( "Empty namespace collection encountered." );
		}
		
		if ($maximumKey === null) {
			// If the key is null, then we return the maximum available
			$keys = array_keys ( $collection );
			sort ( $keys );
			$found = true;
			$foundKey = end ( $keys );
		} else {
			// Otherwise, we optimistically guess that the current version
			// will have a matching namespce. If that fails, we decrement the
			// version until we find a match.
			while ( ! $found && $foundKey >= 0 ) {
				if (array_key_exists ( $foundKey, $collection ))
					$found = true;
				else
					$foundKey --;
			}
		}
		
		// Guard: A namespace wasn't found. Either none were registered, or
		// the current protcol version is lower than the maximum namespace.
		if (! $found) {
			require_once 'Zend/Gdata/App/Exception.php';
			throw new Zend_Gdata_App_Exception ( "Namespace compatible with current protocol not found." );
		}
		
		return $foundKey;
	}

}
